A current hypothesis suggests group A Beta hemolytic streptococcal infection (GABHS) may have an epigenetic role in some cases of tics and Tourette syndrome (TS), acting immunologically as in Sydenham's chorea. Prior studies using immunofluorescent assays of caudate cells or a whole cell cultured neuroblastoma HTB-10 ELISA showed that serological antineuronal antibodies (ANab) occur significantly more frequently in patients with tics, TS, choreiform movements or Sydenham's chorea than in clinical or normal controls. Several studies have found evidence of increased exposure to GABHS in tic groups. In part, this current study was designed to determine in a blinded fashion if a group of TS patients (n=41, mean age 11.3 years) could be differentiated from neurological controls (n=39, mean age 12.1 years), a) using an ELISA based serological assay for antibodies against membrane of HTB-10 neuroblastoma cells to measure ANab, and b) whether evidence of prior GABHS infection was present more frequently in the TS cases as determined by antistreptococcal titers (ASO≥166 and/or antiDNAase B ≥170). ANab levels three standard deviations or more above mean negative control optical density(0.464) were found in 59% of TS patients and 28% of controls (p<0.0063). There was no relationship between positive family history for TS, GABHS titers, or tic severity and ANab presence. Children with TS were significantly more likely than controls to show evidence of antibodies to membrane preparation of HTB-10 neuroblastoma cells. Lack of a relationship to streptococcal antibodies may be related to the cross sectional nature of this study. Clearly any relationship between TS, ANab, and GABHS is complex. Supported by a grant from the Tourette Syndrome Association, Bayside, NY 11361